=SUMPRODUCT Question
 

I've been using =SUMPRODUCT(--(COUNTIF(A1:A1000,B1:B30)0)) to compare
two sets of numbers for matching numbers. Is there a way to expand
this formula to compare 3 or more sets of numbers for matching
numbers? I've tried using it on 3 sets of numbers and keep getting the
error "You've entered too many arguements for this function".

=SUMPRODUCT Question
 

Try this

=IF($C87=0,0,SUMPRODUCT(--(Historical!$A$2:$A$9997="A"),--(Historical!$C$2:$C$9997="B"),--(Historical!$K$2:$K$9997)))

This will sum

Also

=IF($C87=0,0,SUMPRODUCT(--(Historical!$A$2:$A$9997="A"),--(Historical!$C$2:$C$9997="B"))

This will Count

HTH
Mick